Pump



Filed Jan. 2e, 195e a QZQ INVENTORS ATyQRNEY United States Patent() PUMP John Dolza, Fenton, and William- H. Kolbe, Huntington Woods, Mich., asssignors to` General Motors Corporation,.Detroit, Mich., a corporation of Delaware Application January 26, 1956, Serial No. 561,469V

3 Claims. (Cl.` 103--148) The present invention relates to pump means for pumping liuids and more particularly to pump means especially adaptedv for pumping fuel through an injection system for an internal combustion engine.

Some liquids havea very high` vapor pressure and accordingly, tend to vaporize very readily. Formation of vapors in this manner may be Very detrimental under some circumstances such as during a pumping operation when the -liquid is. being transferred from one location to another. When the liquid is drawn into the pump, the pressure in the liquid will be low enough under some circumstances to cause vaporization. of the liquid. The resulting vapors may collect in a stagnant portion of the pumping chamber and/ or the intakes therefor until there is a sufficient quantity of vapor to form a vapor pocket that will block the pumpingV of further liquids. One instance in which this frequently occurs is in` a fuel injection system wherein a,V pump is employed. for` .pumping and/or metering of a liquid' fuel such as gasoline.` The gasoline vapors in the. previous-systems` have tended to collect in the pump etc. and form a vapor lock that prevents proper operation of the pump.. In the event that a Vapor lock does not occur, the presence. of'the vapors will at least effect the efficiency of the pump. and thus'interfere with proper metering of the. fuel;

It is now proposed to provide a pump which is especially adapted for use in pumping liquids that have a strong tendency to vaporize at or near atmospheric conditions.. The pump may include, one or more cells. having self-venting pumping chambers, that will insure a complete discharge of the vapors in the pumping chamber during each pumping cycle. Thus any vapors present in the liquid will be unable to collect in suicient volume to cause any malfunctioning of theA pump. The liquid may enter the pumping chamber through an inlet located at the bottom of the chamber andv leave through an` outlet located at the top of the chamber. Thus if there are any vapors present in the chamber, they` will tend to collect around the outlet and be discharged from the chamber with each vdischarge of fuel. In addition, the inlet and outlet valves may be located asclose asl possible to the pumping chamber. This will allow a small compactpumping chamber thereby permittingy a very high compression ratio even though 'a short stroke. is employed. Thus the fluid in the chamber will be highly compressed and any vapors present therein will condense back into the liquid-` stateand be remixedwi'ththe liquid; In addition, one or more. vertical vent grooves may be formed in the end wall of the pumping chamber so asto extend from adjacent the inlet valve to adjacentthe outlet Valve. Thus even when the liquidis highly compressed, there will always be a passage through the pumpingV chamber which interconnects the intake and outlet Valves and allows any vapors present in the chamber'to rise towards the outlet valve. By placingthe intake-and" outlet valvesron the diametrically opposite sides off the-V pumpingchamber, there will be no stagnant pockets of liquid inthe chamber to collect'vapor-and/or airbubbles:

In addition, the

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intake passageleading to the intakeY valve may compriseV a Vertical passage having a sufficiently large diameter to` allow the fuel to ilow vertically downwardly therethrough at. a very slow velocity. Thus if there are any vapors or air bubbles in the liquid supplied to the pump, they may rise to the top of the intake passage where they Will be separated from the liquid.

In the one sheet of drawings:

Figure l is a cross sectional view of an engine diagrammatically illustrating a fuelv injection system having a' pump therein embodying the present invention;

Figure 2 is across sectional view ofthe pump employed7 in Figure l.

Figure 3 is across sectionalV view of a portion of the pumpV taken substantially along the plane ofline 3-3 in Figure. 2.,

Referringto the drawings in more detail, the present` inventionmay be adapted for use on any suitable internalcombustion engine 10. However-inthe present instance, this. engine 10 is of. theA so-called V type` having a cylinder block. 12 with a pair of. angularlyl disposedl banks of cylinders 14'. The cylinders 14 are charged throughy intake passages 16. in the cylinder heads 18 with the inner ends. thereof forming intakevalve seats 20 in thewalls of the combustion chambers 22 and the other ends communicatingwiththe upper compartment 24 off the plenum chamber 26 containing. throttled air. Thus the induction air may flow through a suitable throttle valve, not shown, into the lower compartment 28, up through-a filter elementlhintothe upper compartment 24 and thence into the intake passages 16.V

In order toform a combustible-charge of air` and fuel, a suitable fiiel injection system 32 may beprovided for discharging fuel into vthe intake` passages 16`where' it will mix with the inductionair.. The. present injection system tinclud'es apump 2,4 that draws fuel from asource such as a storage tank and dischargesr the fuel into a metering and/0r distributingunit 36. for meteringand/or distributing the fuel" to theV various cylinders of the engine 10.-

In the present instance this pump 34 includes a housing 3i8"ad`apted tobe mounted on a vweb 40 extending between thev two banks ofcylinders 14.- The housing 38 may have a chamber 42 in the centerlthereofand a pair of bearings 44 thatare disposed on. the-opposite sides of the chamber 4'2 for rotatably supporting a vertical driveshafl:` 46.l The lower end of the driveshaft46. may project downwardly into lthe camshaft gallery and havena gear-48 thereonfthat meshes with asimilar gear 50 on the camshaft. Accordingly, the driveshaft. 46.will be driven at some fixed ratio to the engine speed.

The housing 38- may includei any desired number of i cylindrical passages 52 which are radially disposed about the pump driveshaft- 46 in a plane normal thereto. The. radially inner ends of. thesepassages 52.- open into the chamber 42. A plunger or piston 54 may be reciprocably disposed in each passage 52. YTheradially inner end of each plunger 54 may engage the workingsurface of acam or eccentric 56 mountedv on the pump driveshaft 46. Thus whenever the engine1'0 `is.operating, the driveshafte 46willvv rotate and cause the cam S6 to reciprocate the. plungers 54 in the cylindrical passages 52.V

A cap 5S may be secured to thehousing` 38over the radially outer endlof each ofthe cylinders SZ-in order to` close this end and togetherwith the plunger 54 form. a4 pumping chamber 60. An inlet passage 62may extend vertically downwardly through the` housing 33'so that one end'will form aninlet 64 in the top of. thehousing 38and' the end vof-athis. passage 62 so Vthat theV face. of thepoppet valve 68 will be in direct communication with the pumpfit the cylindrical walls of the passage 52.

ing chamber 60. An outlet passage 70 may also be provided that extends vertically through the housing 38 with the upper end forming an outlet 72 on top of the housing 38 and the lower end forming an opening 74 in the top of the pumping chamber 60. An outlet valve 76 may be disposed in the outlet passage 70 preferably in direct 'communication with the pumping chamber 60. If both of these valves 68 and 76 communicate directly with the pumping chamber 60, the volume of the chamber 60 will be a minimum and a high compression ratio may be readily obtained even if the plunger 54 has a very short stroke.

In order to improve the pumping action, a resilient plug 78 of some suitable material such as synthetic rubber may be placed in the cylindrical passage 52. This plug 78 is preferably cylindrical so that its exterior will tightly It is preferable that this resilient plug 78 be maintained in a compressed state at all times. Thus even during the intake stroke the plug 78 will resiliently engage the cylindrical walls so as to insure an effective seal against the loss of any lluid from the pumping chamber and bias the plunger 5'4 against the surface of the eccentric 56. In addition, it has been found that by maintaining the plug 78 in a compressed state that the life thereof is greatly improved. One end of the plug 78 may be square so as to engage the end of the plunger 54 while the other end has a concave center or cavity 80 surrounded by a rim 82. The rim 82 seats on the shoulder 84 formed by the cap 58 and the cavity 80 cooperates with a projection 86 on the cap 58. It will thus be seen that the pumping chamber 60 comprises a conical shape having a rounded apex.

As the eccentric 56 rotates, the resilient plug 78 may expand and force the plunger 54 outwardly against the Working surface of the eccentric 56. This will result in the capacity of the cavity 80 increasing and drawing fuel into the pumping chamber 60. Thus the fuel will ow vertically downwardly through the intake passage 62 to the inlet valve 68 where it will enter the bottom of the pumping chamber 60. The vertical portion of this passage 62 preferably has a very large diameter to allow a non-turbulent flow of fuel having a relatively low velocity. Thus if there are any vapors or air bubbles entrained in the fuel, they will be able to rise through the passage 62 to the top where they will be separated from the fuel. Consequently, only pure fuel will be present at the lower end of the inlet passage 62 adjacent the inlet valve 68. Therefore substantially no vapors will enter the pumping chamber 60.

The outlet valve 76 is preferably disposed in communication with the uppermost portion of the pumping chamber 60. Accordingly, if there should be any vapors present in the fuel being pumped, they will tend to rise to the top of the chamber 60. Thus all of the vapors present in the pumping chamber 60 will be discharged through the outlet valve`76 during the compression stroke rather than collecting in the pumping chamber 60.

It should also be noted that when the inlet valve 68 is on the bottom of the chamber 60 and the outlet valve 76 is on the top of the chamber 60, they will be disposed on diametrically opposite sides of the pumping chamber 60. Since the chamber 60 is very thin and the fuel ows from one side to the other, there will be no stagnant pockets of fuel formed in the pumping chamber 60 which will tend to collect any vapors.

In addition, it should be noted that by placing the intake and outlet valves 68 and 76 in direct contact with the pumping chamber 60, the volume of the chamber 60 will be materially reduced. This will make it possible to employ a high compression ratio without a large stroke. Consequently, the pressure in the liquid may be raised sufficiently high to cause any vapors created during the intake stroke etc. to be compressed back into a liquid form and dissolved into the liquid.

As a further deterrent against the collection of vapors in the pumping chamber 60, a vertical groove may be formed in the conical projection 86 of the cap 58. This groove 90 extends vertically upwardly from the inlet valve 68 to the outlet valve 76. Thus even if the plunger 54 is forced into the cylindrical passage 52 and the resilient plug 78 is highly compressed, there will always be a path open for the vapors to rise vertically through the chamber 60 towards the outlet valve 76.

It is therefore quite apparent that a pump has been provided for pumping readily vaporizable liquids in which it is very difficult, if not impossible, for any substantial amount of vapors to ever collect in any pockets inside of the pumping chamber that might form a vapor lock.

It is to be understood that, although the invention has been described with specific reference to a particular embodiment thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

We claim:'

1. A pump structure comprising a housing having a pumping chamber therein, an inlet in one end of said pumping chamber communicating therewith, an outlet in said end communicating with said pumping chamber at a point remote from said inlet, said housing including an end wall having a conical portion projecting partially within said chamber, a resilient plunger disposed in said housing and forming a part of said chamber, said plunger having a conical recess formed in one end thereof and adapted to receive said conical wall portion therewithin, means for applying an axial pressure to said plunger to move said conical recess toward and away from the conical wall portion to pump uid from said chamber, the conical recess surface of said plunger being adapted to engage the conical wall portion at the end of the pump output movement of the plunger, and a groove formed in the conical wall portion, said groove communicating the apex of said conical portion with said inlet and said outlet whereby all fuel and vapor within the plunger recess will be discharged therefrom during the pump output stroke.

2. A pump structure comprising a housing having a pumping chamber therein, an inlet in one end of said pumping chamber communicating therewith, an outlet in said end communicating with said pumping chamber opposite from and at a point above said inlet, said housing including an end wall having a conical portion projecting partially within said chamber, a resilient plunger disposed in said housing and forming a part of said chamber, said plunger having a conical recess formed in one end thereof and adapted to receive said conical wall portion therewithin, means for applying an axial pressure to said plunger to move said conical recess toward and away from the conical wall portion to pump lluid from said chamber, the conical recess having surface to surface contact with said conical wall portion at the end of the pump output movement of the plunger, and a groove formed in the conical wall portion, said groove communicating the apex of said conical portion with said inlet and said outlet whereby all fuel and vapor within the plunger recess will be discharged therefrom during the pump output stroke.

3. A pump structure as set forth in claim 2 in which said inlet, outlet and groove are aligned.

References Cited in the file of this patent UNITED STATES PATENTS @other fermes on following page) UNITED STATES PATENTS Schmidt Nov. 29, 1949 Harvey May 29, 1951 Krall July 31, 1951 De Luca Feb. 17, 1953 Holm July 12, 1955 6 Tarola May 15, 1956 Goss July 10, 1956 Berliner May 14, 1957 FOREIGN PATENTS Switzerland Oct. 16, 1953 

